This invention relates to the new epothilone derivatives of general formula I, ##STR00001## in whichsubstituents Y, Z, R.sup.2a, R.sup.2b, R.sup.3, R.sup.4a, R.sup.4b, D-E, R.sup.5, R.sup.6, R.sup.7, R.sup.8 and X have the meanings that are indicated in more detail in the description.The new compounds interact with tubulin by stabilizing microtubuli that are formed. They are able to influence the cell-splitting in a phase-specific manner and are suitable for treating malignant tumors, for example, ovarian, stomach, colon, adeno-, breast, lung, head and neck carcinomas, malignant melanomas, acute lymphocytic and myelocytic leukemia. In addition, they are suitable for anti-angiogenesis therapy as well as for treatment of chronic inflammatory diseases (psoriasis, arthritis). To avoid uncontrolled proliferation of cells and for better compatibility of medical implants, they can be applied or introduced into polymer materials.The compounds according to the invention can be used alone or to achieve additive or synergistic actions in combination with other principles and classes of substances that can be used in tumor therapy.